1. Field of the Invention
The invention generally relates to the field of anti-tamper devices and methods to prevent or inhibit reverse engineering by an unauthorized user, such as side channel power analysis of an electronic circuit.
More specifically, the invention relates to electronic circuitry that operates in cooperation with existing device compiler outputs and generates a minor output that is used to cancel power fluctuations from a protected electronic circuit as seen external to the protected circuit.
2. Description of the Related Art
It is a known concern of military and commercial entities that reverse engineering and evaluation of an electronic circuit can occur when a proprietary electronic component or device (e.g., a microelectronic circuit) falls into enemy hands or into the possession of a business competitor. The U.S. government has expressly noted such a concern in a recent directive entitled, “DoD Directive 5200.39, Research and Technology Protection within the Department of Defense,” issued in March 2002.
Military opponents or commercial competitors can gain an advantage by learning the operation and vulnerability of a circuit by electronic probing or by physically examining the circuit such as by toggling or testing the inputs and outputs of the circuit to understand, to duplicate it or to develop methods of defeating the circuit.
In view of the above concerns, methods and devices that inhibit the reverse engineering of an electronic circuit (referred to as a “protected circuit” or “protected device” herein) by obscuring on or more of its operational characteristics to an unauthorized user is needed. Such protection is desirable in that it minimizes the ability of an adversary to learn key features and functions of a protected circuit and possibly develop means to disable or copy the device or circuit.
Side channel power analysis is a method of unauthorized reverse engineering (i.e., “tampering” with) of an electronic circuit to identify its key operational circuit characteristics. This form of tampering essentially monitors circuitry power, voltage and/or current variations during various circuit operational modes. These operational variations will result in one or more power, voltage, and/or current variations on the power lines of the circuit in the form of measurable electromagnetic radiation.
Side channel power measurement techniques include direct current/voltage analysis and analysis of direct power drawn from the circuit of interest using, for instance, non-evasive electromagnetic measurement and analysis using an electromagnetic probe as an electronic test probe.
The disclosed method and device of the invention significantly obscures power, voltage and/or current operational variations of a protected circuit and therefore reduces or eliminates the ability of an unauthorized user to perform side channel power analysis tampering of the protected circuit.
The instant invention generally comprises a protected circuit “mirror compiler” that operates in conjunction with the protected circuit output. The mirror compiler outputs are used to obscure or “cancel out” power, voltage and/or current fluctuations as seen external to the protected circuit such as by electromagnetic measurement and analysis.